The invention relates to a machine for filleting fish, in particular fish of differing bone structures.
Fish filleting machines are individually adapted to cut with high yield only a single kind of fish, such as herrings, redfish, Norwegian haddock, and hake, and a few closely related kinds of fish with closely similar bone structure, such as codfish, haddock and ling. The main obstacle to the possiblity of being able to cut fish of different kinds with a particular filleting machine is the different angles at which lateral vertebral appendages extend from the vertebrae of the backbones of fish of differing kinds.
In German Pat. Specification No. 1,454,089, there is disclosed a process and apparatus for severing the flank flesh from the ribs and vertebral appendages of a fish, wherein the rear vertebrae of the fish are engaged and the abdominal cavity of the fish is firmly pressed onto a support in such a manner that the vertebral appendages and ribs are straightened so that each flank forms a plane, whereupon the flank flesh is cut off by insertion of a cutting tool between the skin covering the ribs and the vertebral appendages and the skin enveloping the flesh. However, this process is restricted to fish having vertebral appendages which can be straightened under pressure and which extend from the vertebrae of the backbone at equal angles.
In Norwegian Pat. Specification No. 106,624, there is described a filleting machine in which fillets are severed from the skeleton by back filleting knives and by belly filleting knives, and are separated from the ribs by rib knives arranged parallel to the belly filleting knives. With this machine, it is possible to cut out the ribs in fish of differing bone structures, but the belly filleting knives must cut on both sides of the broadest vertebrae, which entails an appreciable loss of valuable flesh. This is not acceptable when seeking an economical yield from the filleting of fish such as coryphaena hippurus, cynoscion nebulosus, micropogon undulatus or other fish from southern latitudes.